The present invention relates to a method for thinning lines in an image.
In microscopic images of metal crystals, crystal interfaces appear as lines with widths of more than one pixel. Interface lines should be thinned to aid in analysis of images for properties such as particle size. A thinning process should maintain line continuity, because broken interfaces indicate locations where adjacent particles join. Goals of thinning are:
(1) lines after thinning should have a width of one pixel;
(2) lines after thinning should be positioned substantially in the middle of the original line;
(3) the continuity of an original line should be maintained;
(4) the length of an original line should be substantially maintained;
(5) convex and/or concave portions of lines should not result in spikes after thinning;
(6) the thinned lines should not be deformed at crossing locations.
A thinning method, referred to as the Hilditch method, is known but has disadvantages. The method evaluates connectivity of a center pixel as well as connectivity of neighborhood pixels adjacent to the center pixel. The process result has high quality; however, the process speed is low. It is desirable to use faster processing methods.